Recently, research and development of electrophotographic photosensitive members (organic electrophotographic photosensitive members) using an organic photoconductive material have been performed actively.
The electrophotographic photosensitive member basically includes a support and a photosensitive layer formed on the support. Actually, however, in order to cover defects of the surface of the support, protect the photosensitive layer from electrical damage, improve charging properties, and improve charge injection prohibiting properties from the support to the photosensitive layer, a variety of layers is often provided between the support and the photosensitive layer.
Among the layers provided between the support and the photosensitive layer, as a layer provided to cover defects of the surface of the support, a layer containing metallic oxide particles is known. Usually, the layer containing metallic oxide particles has a higher conductivity than a layer containing no metallic oxide particle (for example, volume resistivity of 1.0×108 to 5.0×1012 Ω·cm). Accordingly, even if the film thickness of the layer increases, residual potential hardly increases at the time of forming an image. For this reason, dark potential and bright potential hardly change. For this reason, the defects of the surface of the support are easily covered. Such a highly conductive layer (hereinafter, referred to as a “conductive layer”) is provided between the support and the photosensitive layer to cover the defects of the surface of the support. Thereby, the tolerable range of the defects of the surface of the support is wider. As a result, the tolerable range of the support to be used is significantly wider, leading to an advantage in that productivity of the electrophotographic photosensitive member can be improved.
PTL 1 discloses a technique in which a titanium oxide particle coated with tin oxide doped with phosphorus, or a titanium oxide particle coated with tin oxide doped with tungsten is contained in a conductive layer provided between a support and a photosensitive layer.
Moreover, PTL 2 discloses a technique in which a titanium oxide particle coated with tin oxide doped with phosphorus, a titanium oxide particle coated with tin oxide doped with tungsten, or a titanium oxide particle coated with tin oxide doped with fluorine is contained in a conductive layer provided between a support and a photosensitive layer.